How to Recognise a Poorly Sourced Peptide
Quality differs widely between research peptide suppliers, and the label on a vial reveals very little. Good material is set apart by paperwork you can check yourself, and by the absence of a few familiar warning signs.
Use this page as a checklist before you choose a supplier. It rests on one rule: check the evidence, not the promise.
On this page
Begin with the certificate and its issuer
The strongest single signal is a batch-specific Certificate of Analysis issued by an independent, third-party laboratory. An outside lab has no interest in flattering the result, which a seller testing its own stock cannot claim. A certificate with no named laboratory cannot be checked, so treat it as if it did not exist. Each field is explained in our guide to reading a CoA.
Ask for the raw data
"99% pure" on a product page is a claim. The proof is the HPLC chromatogram, which should show one dominant peak, together with an identity result from mass spectrometry showing that the molecule is the one on the label. A purity figure alone answers only half the question; our purity guide covers the other half.
Warning signs
- A single CoA shown for every order. Genuine certificates cover one batch each.
- Lot numbers that do not match between the vial and the report.
- No identity data: a purity figure is given, but nothing confirms the molecule.
- Prices that cannot add up, far below what properly tested material costs to produce.
- No endotoxin or sterility results for work where cell cultures are sensitive.
- Vague replies when you ask which lab carried out the testing.
What NordPeps provides
Certificates from an independent third-party laboratory are published per batch on our certificates page as they become available, so you can match the lot number on your vial to its report. The aim is plain: the data on file should describe the material on your bench.
Common questions
If I can check only one thing, what should it be?
A Certificate of Analysis for your exact batch, issued by an independent lab that is named on the report. Its lot number should match your vial. It should also carry an HPLC chromatogram and an identity test, done by mass spectrometry or by HPLC run against a reference standard.
Does a lower price mean lower quality?
Not necessarily. But a price well below what properly tested material costs should make you cautious. Rigorous third-party testing is a real expense, and it shows up in the price.